Pulling the spear is the easy part,  tearing it down is something else.....at least the first time through.  I was able to do the retainer with relative ease.
Now came the real fun, removing the gas seal and ball w/spring.  It did not just  simply pull out .....i will keep this short.....do not do anything on the inside near the ball.
I finally decided to go for broke on the outside.......put a screwdriver blade in between tube and seal and twisted blade.......wow it worked right out!

i am typing this because this is the one step i could not find info on what to do.....without destroying the seal!

We have special tools. Spring compressor that is notched for the retainer, lets it turn as well.

After fucking with them for years, I can tell you with out proper tools it's a crap shoot if you don't ruin something.